In many cities there are assistance programs for the elderly, etc. who are truly broke but fines do work well for negligent landlords, fallow properties, etc.

I assume they give warnings first.

Right, but the punishment for not paying taxes is a lot harsher than seems reasonable for someone who just doesn't pay their garbage-pickup bill. It feels weird for those to be the same thing.

I'm gonna guess it'll be treated much like water bills (when the city owns the water processing, anyway). Threaten to call the health authority and child protective services if you don't pay the bill (after all, living in a home full of waste is a health hazard). Put liens on your house and/or car, eventually taking you to court and possibly garnishing your wages. In the meantime, no water service and they'll probably alert other utilities to your lack of payment so you'll either not get turned on or have to pay a deposit.